Many of today's military, space, and commercial electronics designs are required to operate in hostile man-made or natural radiation environments, and in certain extreme cases, a combination of both. Exposure of electronics to ionizing radiation environments can result in catastrophic damage, reduced operating lifetimes, and loss of critical data unless physical protection is utilized to protect the circuitry.
Like electronics, other components that may be maintained onboard vehicles or housed in stationary locations are subject to damage or disruption by ionizing radiation. These include but are not limited to living organisms, micro-mechanical devices, and magnetic, optical, electronic, or organic memory systems.
Steps that are employed during design and production of electronic systems and, to some extent, organic, micro-mechanical, and various memory systems in order to protect those systems from unwanted environmental influences are known as system hardening practices. A key aspect of systems hardening is the attenuation of external ionizing radiation sources by virtue of dedicated radiation shielding. Through a combination of shield material mass, density, and thickness, external ionizing radiation environments may be reduced by several orders of magnitude, thereby reducing the possibility of damage to radiation-susceptible systems.
Housings for electronic and other equipment aboard air, space, and ground vehicles are most often designed with the primary considerations of space and weight limitations. In particular, housings for electronics which must be closely packed within physical structures are often shaped and sized to most efficiently match the structure in or on which the electronics are mounted. Further, housings for electronics used on aircraft and spacecraft are designed to be as lightweight as possible with the thickness, size, and density of the housing only as large as is necessary for structural or thermal protection of the electronics.
Because housings for electronics and other components that may be susceptible to damage from ionizing radiation are not are typically designed with weight and size considerations in mind, they are not often well suited to provide protection from external ionizing radiation. In contrast to the typical goals relating to reduction of weight and size, radiation shielding of unprotected components has traditionally been provided as dedicated housings constructed of high atomic number materials having large mass. Radiation shielding enclosures are typically fabricated from high atomic number metals using specialized stamping, forming, milling, and welding processes which greatly add to the weight and size of the housing. Not only do the radiation attenuating properties of the enclosures require relatively heavy and dense materials, but the enclosures must often allow for design margins due to the lack of availability of precisely sized metal materials with which to construct the enclosures.
What is needed is a method of hardening a system against external ionizing radiation without the need to fabricate dedicated external radiation shields, a process which is both expensive and time consuming.